pontoon bridge vs pontoon

pontoon bridge and pontoon both are nouns.

Word	Noun	Adjective	Verb	Adverb
pontoon bridge	Yes	No	No	No
pontoon	Yes	No	No	No

pontoon bridge (noun)	pontoon (noun)
a temporary bridge built over a series of pontoons	a float supporting a seaplane
	(nautical) a floating structure (as a flat-bottomed boat) that serves as a dock or to support a bridge